After more research, I found that my problem is specific to OpenGL. I can play in D3D, but not OpenGL. Don't really wanna fiddle with DEP but I'll keep it in mind as a last resort.

If you still want to play in OpenGL, do the following:

1) find opengl32.dll in your windows/system32 directory
2) copy & paste it into the "gldrv" folder (should be under steamapps/accountname/counter-strike)
3) now, open drvmap.txt file and delete everything there. After this, type in the following:
gldrv/opengl32.dll OpenGL Driver
4) save, run cs, pick OpenGL. Hope this works for you...
Good luck.All the info taken from here.